hepworth



No Model.)

J. HE'PWORTH.

VARIABLE EXPANSION GEAR.

2 Sheets-Shet 1.

Patented May 31, 1887.

N. PETERS, Fholo-Lilhngmphgr, Washing torn 0,6.

(No Model.)

2 Sheets-Sheet 2.

J. HEPWORTH.

VARIABLE EXPANSION GEAR.

Patented-May 31, 1887.

, Beitknown thatI, JOHN HEPWORTH, of the I city of Montreal, in the district of Montreal the lower end of the four-armed piece in the vention, reference must be had to the annexed UNITED STATES PAT NT I OFFICE.

JOHN HEPWORTH, OF MONTREAL, QUEBEC, CANADA.

VARIABLE EXPANSION-GEAR.

SPECIFICATION forming part of Letters Patent No. 363,825, dated May 31, 1887. v Application filed February 10, 1887. Serial No. 227,148. (No model.) Patented in Canada February 14, 1887, No. 25,998.

To. (ZZZ whom, it may concern:

and Province of Quebec, Canada, have invented certain new and useful Improvements in Variable Expansion-Gears; and I do hereby declare that the following is a full, clear, and exact description of the same.

The object of my invention is to provide-an instantaneous variable cut-off applioableto engines using a D slide-valve, the point of cutoff being automatically regulated by the connection of the operating parts with the governor, the main-valve stem being, as usual, actuated by the eccentric.

The invention may be thus briefly described: Upon the main-valve stem is formed a flat downward extension, on the lower edge of which is a step or projection, and on the face of this extension is pivoted,in its center, a four-armed piece, the upper end of which is connected by a pivot-pin with the riding-valve stem, and the opposite end has attached to it the free ends of two springs secured to fixed parts of the engine, and so arranged that when the cutoff and main valves are in a central position the tension on both springs will be equal. To abracket or standard, serving asthe valve-spindle guide secured to the engine, is pivoted a double crank, to which are pivoted links connected with the ends of tripping-levers, also pivoted to the bracket. To the cross-arms of the fourarmed piece are pivoted stops which are so adjusted that one stop will engage with the step at the foot of the plate to which the fourarmed piece is pivoted, until, when the cut-off valve hasclosed one or the other of the steampassages of the main valve, the movement of the main-valve stem will bring the stop in contact with one of the tripping-levers, thus disengaging it and therebyfreeing the spring which has been in tension,and which will draw opposite direction, throwing over the cutoff valve and instantaneously closing the passage which had been open before and opening that which had been shut.

For full comprehension, however, of the indrawings, forming part of this specification, in which- Figure'l is a longitudinal vertical sectional the piston.

elevation through the cylinder and steam-chest of a stationary engine embodying my invention; Fig. 2, an end view of mechanism actuating cutoff, enlarged; Fig. 3, a detail of fourarmed piecein perspective; and Fig. 4,a detail, also in perspective,'of standard or valve-stem guide to'which the double-crank lever is pivoted.

.Similar letters of reference indicate like parts.

The cylinder, steam-chest and steam-passages, piston, piston-rod, and main-valve action being of any approved construction, no further particular allusion will be made to them. j

A is a standard or bracket, bolted in this case to the upper slide-bar of cross-head, as shown in Fig. 1, to which is pivoted at a the double-crank lever B, the extended end I) of this being connected'by a stud and rod, 12, and bell-crank lever b",or other suitable means, with the governor B. I

O G are tripping-levers pivoted to the standard A, and connected by links 0 O to the double crank B, c a being studs carried on the ends of these levers.

D is the main valve stem, D an extension formed on same, and D a step or projection formed on the lower end of such extension.

E is the cross or four-armed piece, pivoted V at e. to D, and carrying on the ends of its side arms stops F F, pivoted to them. The end of the upper arm is pivoted to the stem G of the riding-valve H, and to the end of the lower arm are attached the ends of two springs, J J, having their other ends connected to fixed points.

- The valve H is usually, as shown in Fig. 1, formed with an intermediate throat-piece, h, corresponding with a similar piece in the passage of the main valve, and upon the ends of the main valve are formed seats K K, between which and the ends of the valve H are spaces K K, in which the steam will form a cushion, so as to prevent too sharp an impactof the valve when drawn over.

The operation of my invention is as follows: The parts are, as shown in Figs. 1, 2, and 3, in the several posit-ionsthey assume when the piston is at the beginning of its back-stroke, the main valve traveling in the same direction as So soon as (in this case) the stop ILO F, carried in the side arm of the four armed piece E, comes in contact with the stud c, it is knocked off the step or projection D, thereby releasing the four-armed lever E, and allowing the spring J, which has been in tension, to draw over the end of the lever E, to which it is attached, and instantaneously reverse the position of the riding or cut-ofl' valve, thereby cutting off the steam from the port in the valve which had previously been open, and opening that which had been closed. It will be seen that at the time of cut-01f the ridingvalve has no pressure, as it is in equilibrio with the steam underneath.

The action of the governor in regulating the speed serves to bring together or widen apart the ends of the trip ping-levers O 0, ac cording as the speed at which the engine is traveling increases or diminishes.

Concussion from the impact of the cut-off valve H against the main valve is preventedby the steam in the recesses K K forming cushions to receive it. i It must be understood that although I have in this description and the drawings hereto annexed shown and'desoribed my invention as applied to a D-valve, it is equally applicable to every kind of slide or piston valves.

Having thus described my invention, I beg to state that what I claim is as follows:

1. In asteamengine, the combination of the following elements, viz: a downward extension on main-valve stem, a lever pivoted to such extension and having its upper end pivoted to stem ofriding-valve and lower end connected by tension-springs with fixed points on the engine, and means for holding such lever and releasing it by action of main-valve stem, all substantially as herein described, and

for the purposes set forth.

2. In a steam'engine, the combination of the following elements: a bracket or standard secured to engine, a double crank pivoted to to stem G, springs J J, pivoted to its lower end, and stops F F to its side arms, doublecrank lever B, and tripping-levers G G, pivoted to bracket A, and link 0 0, connecting said levers with crank, all as herein described, and for the purposes set forth.

JOHN HEPWORTH. Witnesses:

OWEN N. EVANS, W. P. MoFEAT. 

